The director of the U.S. National Security Agency, Army Gen. Keith Alexander, testifies during a Senate Appropriations Committee hearing on Capitol Hill, June 12. / Mark Wilson Getty Images

by Oren Dorell, USA TODAY

by Oren Dorell, USA TODAY

WASHINGTON - Army Gen. Keith Alexander, director of the National Security Agency, defended his agency, saying what his staff does "is bring back more U.S. soldiers, airmen and Marines" alive from dangerous postings.

"We see the threats coming at this nation," Alexander said.

"We see what neither the CIA nor FBI could see" before 9/11, Alexander said. "We help them connect the dots."

In just five months, terrorists have killed thousands of people in Pakistan, Iraq, Yemen and Libya, he said. "And yet not one major terrorist incident in the United States since 9/11. That's not by accident," Alexander said.

The NSA has been in the spotlight over accusations that it monitored the phone calls of leaders who are U.S. allies and is sweeping up phone transactions of millions of Europeans as part of an anti-terror surveillance program.

The NSA on Sunday denied a report in the German tabloid Bild am Sonntag, citing unnamed intelligence sources, that President Obama was told by Alexander in 2010 that German Chancellor Angela Merkel's phone was being tapped and that Obama allowed it to continue.

Alexander was joined by James Clapper, director of the Directorate of National Intelligence, who also said he preferred not to discuss the once-secret programs but said he now welcomed the debate.

"We believe we have been lawful," Clapper said. "What we do not do is spy on Americans or innocent civilians of any country."

Obama ordered a review of the NSA data-collection program, but Alexander said assertions that the NSA collected tens of millions of phone calls of U.S. allies in Europe "are extremely false."

Those reports were based on a screenshot "where the person looking at it didn't know what it was looking at," he said.

The information collected was collected by NATO allies on other countries where they were involved in military operations with the United States, Alexander said.

"This is not information we collected on our European citizens. This is information collected by our NATO allies and shared with us in ongoing military operations in which NATO participated," he said.

The Wall Street Journal reported on Sunday that the NSA stopped a program that intercepted the communications of Merkel and other European leaders after an internal White House review informed the president this summer of the extent of the surveillance.

The report, which cited unnamed U.S. officials, followed a day of upheaval in Europe, as German and French officials criticized the United States for the alleged extent of the NSA surveillance, which was reported in several European publications.

Some committee members faulted the officials for not being forthcoming enough about the programs Congress was supposed to be overseeing.

Rep. Jan Schakowsky, an Illinois Democrat, complained about learning certain elements of the NSA program from the media, and pledged to change the program.

"We did we not know that heads of state were being eavesdropped on, spied on," Schakowsky said. "It's a policy issue that has very broad implications and â?¦ we did not know that."

But Rep. Mike Rogers of Michigan, the Republican chairman of the House Intelligence Committee, has called criticism of the U.S. intelligence operations from European leaders "disingenuous.''

"It's a good thing," he said Sunday. "It keeps the French safe, it keeps the U.S. safe. It keeps our European allies safe. This whole notion that we're going to go after each other on what is really legitimate protection of nation-state interests I think is disingenuous.''